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Topic Review (Newest First)

01-17-2011 09:28 AM

1971BB427

A couple things can cause the mixture screw to not affect idle. It could have a vacuum leak, or it could be a worn seat in that side and it's still flowing with the screw all the way in. Try gently seating it with a little pressure, then back it out a couple turns and see if that helps.
Check for leaks around the carb with starting fluid sprayed at the base to see where it might be sucking air.

01-16-2011 08:34 PM

cucumber1949

Also check to make sure the mixture screw and seat are not contaminated with dirt which may be keeping the mixture screw from closing all the way. If you suspect this check out the following from the Edelbrock website.

The manual has the best instruction for tuning the edelbrock afb. Follow it and it will work well.

about 1.5-2 turns out . Make sure the engine dies with the ides screws all the way in. If not it is pull past the idle ports. The screws only effect idle mixture. Nothing else.

The exhaust leaks must be fixed .

01-12-2011 03:57 PM

bigdog7373

Well, the header leak may have some impact on it because that bank of cylinders has less exhaust restriction and in turn makes slightly more power which means it needs more fuel. Fix it and see what happens.

01-12-2011 03:22 PM

fast68

edelbrock mixture screw

got an edelbrock 4bbl on an old sbc

with it running the pass side screw can be screwed all the way in and the engine doesnt stumble or anything

but it does stumble when the driver side screw is turned in

what does this mean?

also the pass side exhaust has a bad rotten leak at the shorty header collector in which is what we have the truck here to fix already anyways